The parallel arrangement of brads in a collated strip for use in fastener driving tools is generally known. The collated strip of brads is usually made coherent by means of suitable adhesive material, such as for example, nitrocellulose, and is disposed in a magazine of the fastener driving tool wherein individual brads are sequentially fed into a channel of a nose-piece thereof. A driver blade is accelerated axially through the channel behind the brad and into engagement therewith so as to separate the brad from the collated strip and discharge the brad from an aperture of the nose-piece into a target material or workpiece, usually grained wood or particle board. Many powered finishing nail, or brad, driving tools have the magazine oriented at a right angle relative to the channel in the nose-piece. Other fastener driving tools advantageously aftwardly sweep the magazine from the nose-piece at an angle relative to the channel therein so as to improve clearance about the nose-piece and to facilitate handling and operation of the fastener driving tool, particularly while performing nailing operations in closed spaces, such as along corners of intersecting walls and ceilings. A fastener driving tool having a swept magazine configuration for accommodating a collated strip of brads is disclosed in co-pending U.S. application Ser. No. 08/883,087 filed on Jun. 26, 1997, entitled "Pneumatic Trim Nailer" which is incorporated hereinby reference thereto.
To accommodate fastener driving tools having an aftwardly swept magazine, the collated strip of brads must be arranged obliquely so that a leading edge of the collated strip of brads has substantially the same angular relationship, usually within two degrees more or less, to the longitudinal axis of the brad as the channel of the fastener driving tool nose-piece has to the magazine. U.S. Pat. No. 4,664,733 entitled "Method of Manufacturing Cohered Fasteners" issued on May 12, 1987 to Masago, for example, discloses a machine for offsetting a plurality of preformed fasteners adhered together with a plasticized adhesive coating so as to form a strip of obliquely cohered fasteners before the adhesive coating hardens. The result is a collated strip of brads arranged obliquely and having a first stepped edge formed by the plurality of brad points and a second stepped edge formed by the plurality of brad heads. The point of each brad has a straight edge symmetrically formed by converging surfaces extending from opposite sides of the brad, wherein the edge is perpendicular to the longitudinal axis of the brad and is parallel to an upper surface of the head. The process of U.S. Pat. No. 4,664,733 however requires complex machinery and additional processing steps that increase production costs.
Other known methods of forming obliquely collated strips of brads for use in fastener driving tools having an aftwardly swept magazine include forming points on a parallel arrangement of wire members with a stepped cutting die oriented at an appropriate angle relative to the longitudinal axes of the wire members. According to these alternative methods, heads of the brads are formed on an opposite end portion of the wires with a stepped heading die, wherein the end portions of the wire members on which the heads are formed are cut with the same stepped cutting die used to form the points. In the known prior art, the point of each brad is formed either having a straight edge defined by converging surfaces extending from opposite sides of the brad as in U.S. Pat. No. 4,664,733, or the point of each brad is formed having a flat surface perpendicular to the longitudinal axis of the brad. In both configurations, however, the resulting obliquely collated strip of brads has a stepped edge formed by the plurality of brad points and another stepped edge formed by the plurality of brad heads, wherein each individual brad is configured substantially the same as those discussed above in connection with U.S. Pat. No. 4,664,733. Although these alternative methods of forming obliquely collated strips of brads has advantages over the method of U.S. Pat. No. 4,664,733, including reduced manufacturing costs, they are nevertheless subject to some drawbacks. More particularly, the stepped cutting dies are expensive to fabricate. Additionally, variations in the diameters of the wire members causes misalignment of the stepped cutting and stepped heading dies relative to ends of the wire members during the cutting and heading operations. Misalignment of the stepped cutting die results in over-cutting of some wire members and incomplete cutting of others, which causes excessive wear on the cutting die and may prevent proper separation of the formed obliquely collated strip of brads from the wire members during the manufacture thereof. Misalignment of the stepped heading die results in the formation of incomplete and distorted heads on the cut wire members, and causes excessive wear on the stepped heading die.
In addition to the problems discussed above, the inventor of the present invention recognizes that improperly formed brads are susceptible to jamming in the channel of the nose-piece, and moreover are a suspected cause of poor penetration performance, possibly resulting from slippage of the driver blade off the head during fastening operations and from poorly formed points. Notably, in the past, it was generally believed that fastener points must be formed symmetrically in order to ensure adequate and accurate penetration into the workpiece, and that asymmetrically formed fastener points had an increased tendency to be deflected from the surface of the workpiece, a phenomenon referred to as skating. Asymmetrically formed points were also believed to be more susceptible to influence by wood grain, sometimes piercing through a side of the workpiece, which is an adverse effect known as shining.
The present invention is drawn to advancements in the art of brads formable into an obliquely collated strips of brads, combinations thereof, and methods of making the same, which overcome problems in the prior art.